Dan Martin moves up to ninth as Froome keeps yellow jersey

When Chris Froome was asked on Thursday what he had to do to win his third Tour de France, he said one thing: stay safe. It was not a casual comment given the weather forecast for the third Alpine stage on Friday: thunderstorms and low cloud. The race leader's fears were realised when he crashed on the final descent before the finish here, although not his worst fears as he managed to increase his overall lead after a separate crash destroyed the chances of the overnight runner-up Bauke Mollema.

Given the circumstances, once his injuries had been assessed, Froome could treat the loss of 36sec to the stage winner Romain Bardet with a degree of equanimity, as he ended the day with the Frenchman in second, 4min 11sec behind. His fellow Briton Adam Yates remained in the best young rider’s white jersey after finishing just behind the yellow jersey.

Yates suffered a mechanical problem earlier in the stage and slipped to fourth overall behind Froome, Bardet and Nairo Quintana, who attacked on the final climb but was unable to open a decisive gap on the race leader. The fight to be runner-up is down to these four and the Australian Richie Porte. With 1min 06sec between second and fifth, all bets are off for the final Alpine stage on Saturday.

Etixx-Quick Step's Dan Martin went on a late attack in a bid to secure a stage win but couldn't make up the ground on Bardet as the steep ascent got the better of him.

The Irish rider finished seventh in the stage, 28 seconds behind the winner but moved up to ninth in the overall classification, seven minutes and 10 seconds behind Froome.

Froome’s front wheel slipped on a white line on a left-hand bend 11 kilometres from the finish, shortly before the foot of the drop down from Megève to the valley before the final first-category ascent to the finish. The yellow jersey plunged over his handlebars and fell heavily on his right shoulder, ripping his yellow jersey on its right side, grazing his elbow and his hip.

Vincenzo Nibali lost control in precisely the same spot, sliding down the road, and stopping just before he reached Froome. As when he crashed at Mont Ventoux – while going uphill – Froome was again forced to his feet, this time briefly in order to change bikes with his team-mate Geraint Thomas, who pushed him off to minimise his time loss.

The treacherous conditions hit the race on the final descent, and were merciless for those without support as team cars were caught up well behind the lead group. Shortly before Froome’s crash, Mollema had lost control approaching a right-hand bend and had to come almost to a halt as his trajectory took him straight on at the corner, although fortunately he stopped before colliding with a road sign. The Dutchman had no team-mates in support – Froome, in contrast, had four men around him at the crucial moment – which meant he struggled horribly to get to the finish line, losing 4min 26sec and dropping from second to 10th overall in one fell swoop.

In the confusion after Froome’s crash, Bardet escaped to link up with his team-mate Mickaël Chérel, who had figured in an earlier escape, although he came close to grief as the pair sped away, hitting Chérel’s back wheel and almost colliding with a parked car. He opened a lead of 1min 24sec on the steepest section of the climb, but sustained attacks within the group around Froome trimmed that to 23sec at the line.

“Bardet jusqu’au bout,” proclaimed that morning’s l’Equipe as if anticipating the result; the whippet-thin climber in the Ag2R team was France’s last man standing after Thibaut Pinot’s illness and the crashes which had affected Warren Barguil. En route to the line he swept up the former world champion Rui Costa for an opportunist win that sits well alongside his victory last year at Saint-Jean-de-Maurienne and which places him in pole position to finish second behind Froome on Sunday in Paris.

As Bardet forged ahead, the battle for the podium hotted up. Froome had struggled at the foot of the climb but was ably supported by Wout Poels, and he hugged the Dutchman in gratitude as they crossed the line. Porte put Damiano Caruso to work and tried to dislodge his friend and former team-mate Froome, but he had had to work hard on the descent from the super-category Montée de Bisanne after puncturing, just as Nibali and his Astana team-mates were pilling on the pressure.

The Australian’s legs buckled late on and he crossed the line 53sec behind Bardet while Quintana again did his utmost, but Froome kept his losses to the minimum. The yellow jersey appeared on the podium with his knee bandaged, and refused interviews after the stage.

Froome was far from being the only crash victim. The double stage winner Thomas Dumoulin fell – a touch of wheels as the road went uphill – and was forced to pull out, which could have implications for the Olympic time trial in Rio. On Saturday, when the race finishes down the Col de Joux-Plane in Morzine, at the foot of 11km of the tightest hairpins in the Alps, more thunderstorms are forecast. Nerves will be on edge until the final kilometre.

Stage 19 top 10

1. Romain Bardet (AG2R) 4:14:09”

2. Joaquim Rodriguez (Katusha) +22”

3. Alejandro Valverde (Movistar)

4. Louis Meintjes (Lampre)

5. Nairo Quintana (Movistar) +25”

6. Fabio Aru (Astana) +27”

7. Daniel Martin (Etixx-Quick-Step)

8. Wout Poels (Team Sky) +35”

9. Chris Froome (Team Sky)

10. Richie Porte (BMC Racing) +52”

General Classification after Stage 19

1. Chris Froome (Sky) 82:10:37”

2. Romain Bardet (AG2R) +4:11”

3. Nairo Quintana (Movistar) +4:27”

4. Adam Yates (Orica) +4:36”

5. Richie Porte (BMC Racing) +5:17”

6. Fabio Aru (Astana) +6:00”

7. Alejandro Valverde (Movistar) +6:20”

8. Louis Meintjes (Lampre) +7:02”

9. Daniel Martin (Etixx-Quick-Step) +7:10”

10. Bauke Mollema (Trek) +7:42”

(Guardian service)